The overarching goal of the proposed research is to understand the representations supporting executive control and its development during childhood. Although mature humans show unique abilities to flexibly adapt their behavior to changing circumstances, children can show stunning failures to do so. For example, children often perseverate, repeating prior behaviors when they are no longer appropriate. Much progress has been made in studying the remarkable developments children show in executive function. However, a unified framework is still needed for understanding the cognitive processes and neural factors underlying these developments. The proposed research builds on a biologically-based computational modeling framework for understanding the development of executive control. This work investigates the hypothesis that two critical factors in the development of executive control are the emergence of increasingly abstract, rule-like representations and increasing abilities to maintain information in an active form, both of which rely on prefrontal cortical developments. These issues are investigated through behavioral studies with children, neuroimaging studies with adults, and neural network models tested at different points in development. This approach will allow us to better understand components of executive control and their development, at the cognitive, computational, and neural levels. We pursue these aims: Aim 5.1: Investigating Relations among Abstract Representations, Active Representations and Executive Control During Early Development These studies with children and developing neural network models address critical questions from preliminary work on these factors, and systematically evaluate early developing relations among these factors. Aim 5.2: Investigating Effects of Manipulating Abstraction and Active Maintenance Abilities During Early Development These studies with children and developing neural network models focus on effects on executive control of manipulations designed to enhance or interfere with components of executive control. Aim 5.3: Investigating Neural Components of Executive Control Representations These studies in adults and fully developed neural network models assess the neural substrates and signatures associated with representations supporting executive control. The proposed work provides a coherent program for advancing understanding of the relations among components of executive control, and developmental changes in these components and relations. This is an essential step in understanding our uniquely human executive function abilities and factors that lead to their enhancement or impairment, and in turn informing applications for both typical and special populations.